The goal of this project is to facilitate the development and evaluation of statistical methods for identifying and characterizing the genetic contribution to complex diseases and their precursors and risk factors. We will pursue this goal by continuing the organization of the Genetic Analysis Workshops (GAWs), which began in 1982. The GAWs are a collaborative effort among genetic epidemiologists to evaluate and compare statistical genetic methods. For each GAW, topics are chosen for their relevance to current analytical issues in genetic epidemiology, and sets of real and computer-simulated data are distributed to investigators worldwide. Participants submit the results of their analyses, which are discussed and compared at a 2.5-day meeting. Before the Workshops, participants communicate with others who have done similar types of analyses and plan integrated presentations. The GAW submissions invariably contain new ideas for methods to handle complex phenotypes. Recent GAWs have included genome scan data and simulated sequence data, giving participants an opportunity to try out new methods for localizing disease-causing genes. GAW13 (to be held in 2002) will feature genetic analysis of longitudinal data from families in the Framingham Heart Study, together with multiple replicates of a simulated data set modeled after the Framingham data. GAW14 will be held in 2004 and GAW15 in 2006. All planning and data distribution for GAW16 will be essentially complete by the end of the requested period of support in 2008. We will continue to distribute real and simulated data from past GAWs and programs for genetic analysis. Long after each GAW is over, investigators continue to use real and simulated GAW data sets to evaluate new analytical methods and software, to estimate power and false positive rates, and to demonstrate the feasibility of statistical techniques for finding disease genes. GAW data also are extensively used in teaching and dissertation research.